Other Guitars

Support for unsupported archtops?

1

I have a 1960 Silvertone H63, same as the Espanada, black with two P-13 pickups. It has no bracing on the back side of the top and some of the typical bridge sag you'd expect after 57 years. I'm in the process of making a shim to raise the bridge pickup to get similar output to the neck. I got to thinking after looking into various types of bracing on Gretsch guitars that a block similar to the one that bridges the gap between front and back in trestle bracing might help at least stabilize the situation, reduce likelyhood of feedback, and maybe help with tuning stability. I'd prefer something I could accomplish without taking the top or back off the guitar, go through the bridge pickup opening I think. I think I could use some plasticene to make an impression of top and back curvature to give myself some guidelines for the necessary size and shape. I'm guessing the gap is wider toward where I'd have to insert it through the pickup opening and narrows as I would slide the peice towards the bridge/tail hopefully finding its installation location near the bridge. Any advice?

2

A shim underneath the bridge pu is always a good idea to get the PUS to have same output. If you cannot make one yourself, ask boardmember Paul Setzer

Dont take off the top or back that is much too drastic and very hard to do. On an electric a sagging top is not nice to see, but usually not a big structural problem either.

If you want to have the same effect as the Gretsch tresle bracing just install a soundpost , you have easy access through the pickup hole indeed. Glue a (well fitted) block to the inside back underneath the bass side bracing. Then install a post in between the brace and that block. Take your time when fitting. To short and itll fall out. Too long and itll crack your top !! Dont try to raise your top to the original position. It wont work youll just end up braking it.

So careful there. It should just be long enough to fit with the slightest of pressure. So try to fit, take out, sand, try to fit etc. Repeat until perfect. You dont have to glue it in. When you string up, the pressure of the strings will keep it in place

If youre not confident have a luthier do it.

3

Maybe even talk to a violin repairer. All violins, 'cellos, double basses etc have a soundpost under the bridge. People who repair these instruments have tools specifically designed to fix soundposts inside instruments through the F-hole. The positioning of the soundpost in a classical instrument is quite critical to the sound, but with a laminated guitar as long as the post sits under the bridge I am sure you'll be fine.

I think installing a soundpost is an excellent idea.

4

You could make your mods, then fill the guitar up with that expandable spray foam insulation that comes in a spray can, that should stiffin it up and stop any feedback. SERIOUSLY DON'T DO THAT. A few years ago I ran across a 67 Gibson ES335 priced right so I go look at it and the 80 year old guy had owned it since it was new. He didn't like the feedback from the hollow body so he used the spray foam insulation and filled up the guitar. It made me kind of sick to my stomach to see that. I really like those old Harmony hollow body electrics. Let us know if you come up with a bracing solutuion.

5

JimmyR is pointing the right way...

First step is to have someone with the tools and skills to look at the options.

6

If you take the pickups out, there is some room to put some small braces and soundposts down to the back. To make these guitars really play, usually takes a bit of work. Mostly neck joints, extra bracing, neck straightening, pickup height adjustments etc YMMV

7

The neck angle seems okay and it plays well as far as the action. The main things that need to be remedied are tuning stability and adjusting bridge pickup height. I bought a set of replacement pickup surrounds which will give me some shims to work with, existing surround stacked with the thinner neck one or two neck surround heights. I'm going to start with that and have my local luthier do a thorough once over and setup and see if the tuning stabilizes.

The top is pretty thick laminate but has no bracing on the underside. My thought was some amount of give in the top might be contributing to tuning instability and some bracing would help stabilize that. I'll try to eliminate other possibilities first.

8

Gregory:

A picture might help, from the side, showing bridge height and p/u. I'd compare it with my Silvertone 1427 (much the same guitar), see if there's any difference. MD

9

I'm all for installing a sound post to improve sound and response but rarely have heard of it causing tuning instability. The strings put a lot of pressure on the top for it to be moving enough to cause instability while playing. I'm not saying it's not possible, I just haven't encountered it.

Have you improved the bridge, nut, and tuners? Those will have the biggest effect on tuning stability.

Again, I could very well be wrong. It just surprises me that a fully strung guitar would be flexible enough to cause that kind of instability. I've had harmonys, kents, lyles, etc in the past with top caving and unevenness, but that didn't affect tuning (those aforementioned parts did however).

10

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I glued these two sound post in my old '61 6124. With a little trimming and dry fitting you can get them just right. Then glue them in.

11

Cirecc - Thanks, I need to go over the other possibilities of tuning problems for sure. And Setzer, thanks for the project pics. Using a mirror thru the F hole I couldn't see any paralell top bracing to connect with, but thats the general idea of what I was thinking of adding.

12

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I glued these two sound post in my old '61 6124. With a little trimming and dry fitting you can get them just right. Then glue them in.

– Setzer

Did this increase the bass response of rthe guitar? I'm thinking of putting a sound post in my old 6124.

13

About a week ago I went to a shop to check out a Silvertone "Espanada" similar to the one you're working on. It was original and looked good (at first), and was priced right. After playing it and upon closer inspection, it was suffering from some of the same problems as yours. The top was definitely sagging under the bridge and bridge pickup. This explained why the bridge pickup polepiece screws were screwed almost all the way up, and the bridge saddle was up so high on its posts that it was tipped forward at about a 30 degree angle. It had heavy strings on it with a wound G, and for me the action was terrible (I'm used to playing 10s). The pickups sounded really weak as well (probably because they were so far below the strings). The neck heel was beginning to separate from the body, and it needed a refret. I looked at it long and hard, but ultimately decided to walk away from it. It was a cool looking guitar, but it needed far to much work that was way beyond my skills.

14

I'ts hard for me to believe that you're guitar doesn't have any internal bracing bars under the top. I bought a Harmony wreck '50s bottom end acoustic a few years back. Even that one had parallel bars extending either side of the neck. If you can't feel something like this thru the f-holes you have a hopeless guitar, get rid of it.

In guitars, the tone post is used to control feedback, not so much as supporting structure.

Lee

15

Yes from looking and reading online Harmony didn't use bracing on the underside of the tops of these models. I had a similar problem with a 1952 ES 295 (refin) I used to own. (sunken top) Just shimmed the bridge pickup and it worked pretty well. Which is where I'm going to start with this one. When I asked my local tech about it he didn't think it was worth trying to put bracing in after the fact saying "it will never be a Gibson."

It seems to have a decent neck angle and the action is decent once you get used to the club like neck. I think I'll first have my tech do a good setup and shim the bridge pickup and see if I can get it to stay in tune and play and sound decent before doing anything else. Tuning and bridge pickup volume where the only playability issues I noticed. It sounds like adding a sound post will be mostly desireable if I'm having feedback issues and trying to add paralell bracing a lot of work and /or money. The top and back are really thick plywood which I'm thinking will also tend to discourage feedback.

16

I had an H63 about 6-7 years ago. I remember reading somewhere that it didn't have bracing under the top, but I don't think I ever actually checked. But after doing some googling on the subject, I'm not so sure. Maybe it had some sort of bracing, just not the standard parallel bars one would expect. Apparently Harmony had some peculiar and not always practical ideas about bracing. I didn't find any solid info on what's under an H63 top, but here are a couple of pages I found interesting.

http://harmony.demont.net/k...

http://harmony.demont.net/k...

17

This makes me wonder if the H63 "bracing" might not be a larger rectangular plate and even shorter bars to the rear, which obviously don't seem like a great bracing approach.

18

Thanks Afire. I had seen the one on the Roy Smeck model. I wasn't able to see any bracing using a mirror and a flashlight. Maybe I should go in with an endoscope to be sure. They had some great interior views in that article. I could see fabricating some bracing I could install with sound posts but I also think that would take a tremendous amount of time for me to get right.

19

Did this increase the bass response of rthe guitar? I'm thinking of putting a sound post in my old 6124.

– Journeyman

Jman, it tightened up the bass as I recall and evened everything out like a closed topped Tennessean, this was with foam F hole plus too.


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